1. Field of the Invention
The present invention relates generally to an image management method and system using a thumbnail in a Digital Living Network Alliance® (DLNA) system, and more particularly, to an image management method and system which can increase user convenience by reducing a display time of a thumbnail in a DLNA system.
2. Description of the Related Art
DLNA conforms to standards of IEEE 802.3i, IEEE 802.3u, etc. for wired network connections and to standards of IEEE 802.11a/b/g for wireless network connections. In DLNA, a network layer uses Internet Protocol version 4 (IPv4) and a media transport layer uses HyperText Transfer Protocol (HTTP). DLNA is based on Universal Plug and Play (UPnP) which is a middleware employing protocol such as Internet Protocol (IP), Transmission Control Protocol (TCP), User Data Protocol (UDP), HTTP, and eXtensible Markup Language (XML). UPnP has a characteristic of enabling devices on a network to perform command and control functions with each other independent of a specific operating system, programming language, and media.
The UPnP Audio/Video (AV) standard defines four services: a connection manger service, a rendering control service, an AV transport service, and a content directory service.
The connection manager service allows a control point to use and manage a relationship between a source and a sink of content in order to select format and protocol. The control point refers to a device which is capable of discovering and controlling other devices. The connection manager service doesn't care if the control point is not aware of physical media connection techniques and allows the control point to select a source and a sink for reproducing the source.
The rendering control service controls sound and image characteristics. Most playback devices provide setting attributes that affect the playback of content and the rendering control service allows the control point to provide a function for controlling the playback attributes.
The AV transport service controls playback and recording. The AV transport service provides a mechanism for enabling the control point to control transmission of audio and video streams through functions such as play, stop, pause, etc.
The content directory service shows audio and video content and a metadata list. The control point uses the content directory service to search and store the audio and video content. The content directory may list various media types, such as songs stored on an MP3 player, slides of still images, movies stored in a DVD-juke box, TV schedules, etc.
In the content directory service, a method for dynamically generating thumbnails for image items and efficiently playing back the generated thumbnails through a control point or a media renderer has been described. In DLNA, thumbnails are provided mainly in an independent media format of JPEG_TN or PNG_TN.
The thumbnails refer to small-size images relative to original images and are used to simultaneously display a plurality of images or to preview the images. A thumbnail image has an advantage in that it is capable of rapidly obtaining information about an original image because the contents or features of the original image can be known without uploading the original image to a memory. Although a thumbnail cannot provide accurate information due to its image size or picture quality, efficiency of information display can be increased by a function of re-displaying an original image selected by an approximate information analysis result obtained through the thumbnail image.
In the existing DLNA standard, thumbnails are regarded as independent images in a media format of JPEG_TN or PNG_TN. Images on a digital media server are expressed as meta information in XML format, and information about locations capable of receiving images is recorded in the meta information together with information such as names and resolutions of the images. In this case, Uniform Resource Identifier (URI) information indicating the location of an original image and information indicating image information of thumbnails are added to the meta information. A client may download an original image file by accessing a corresponding URI and may display thumbnails on a screen.
The following Table 1 and Table 2 describe a thumbnail in a DLNA standard according to the prior art.
TABLE 17.3.55.3 If a UPnP AV MediaServer exposes thumbnailimages for image or video content, then a UPnP AVMediaServer must provide a thumbnail that conforms to requirementJPEG_TN media format profile and be declared with theJPEG_TN designation in the fourth field of theres@protocolInfo attribute.
TABLE 27.3.55.5 A UPnP A/V Media Server must not expose a<res> element with a thumbnail media format profileID (i.e. JPEG_TN, PNG_TN), withoutexposing at least one additional <res> element witha media format profile ID that is not one of the thumbnailmedia format profile IDs.
If a client desires to display an image list that is shared in a digital media server on a screen by using thumbnails, the client may request the digital media server to transmit a browse or search action provided in a content directory service and may receive XML documents including information about the image list. The client receives thumbnails by generating respective new network connections for all thumbnails to be displayed on a screen. However, if a network environment does not provide fast response time and large bandwidth capacity, displaying thumbnails consumes considerable time and causes user inconvenience.